'Wasteful' galaxies launch heavy elements into deep space

'Wasteful' galaxies launch heavy elements into deep space”

After scientists studying potentially wasteful galaxies ran a series of complex computer simulations, they found that galaxies, both the Milky Way and others, are not almost as efficient as retaining their raw elements as scientists had previously believed.

According to a report from Phys.org, a study from astronomers at the University of Colorado, Boulder reveals that elements including oxygen, carbon and iron are much more abundant in the outer halos of galaxies than within the galaxies themselves.

And sweeping those huge amounts of heavy elements a million light-years into space required a strong breeze - at least 1,500 kilometres per second, they calculated - generated by a galaxy's central supermassive black hole and exploding stars.

"Previously, we thought that these heavier elements would be recycled in to future generations of stars and contribute to building planetary systems", said Benjamin Oppenheimer, a research associate in the Center for Astrophysics & Space Astronomy (CASA) at CU-Boulder and lead author of the study. The galaxies, in effect, release more minerals and elements into the universe than they themselves need to build stars, planets and even life.

The near-invisible reservoir of gas that surrounds a galaxy, known as the circumgalactic medium (CGM), is thought to play a central role in cycling elements in and out of the galaxy, but the exact mechanisms of this relationship remain elusive. While the average galaxy can be up to 100,000 light-years across, the CGM can range up to a million light-years.

The Cosmic Origin Spectrograph (COS) was the element in NASA's Hubble Space Telescope that helped the team obtain the necessary data to evaluate the inside of the circumgalactic medium and perform simulations. Regardless, both types of galaxies are home to (and the creators of) tens of thousands to hundreds of billions of stars.

"The remarkable similarity of the galaxies in our simulations to those targeted by the COS team enables us to interpret the observations with greater confidence", study co-author Robert Crain, a Royal Society University Research Fellow at Liverpool John Moores University, said. "The high temperatures, topping over one million degrees Kelvin, reduce the fraction of the oxygen that is five times ionized, which is the ion observed by COS".

By contrast, the temperature of the CGM gas in spiral galaxies is 300,000 degrees Kelvin, or around fifty times hotter than the surface of the Sun.

"This is a violent and long-lasting process that can take over 10 billion years, which means that in a galaxy like the Milky Way, this oxygen we're observing has been there since before the Sun was born", Oppenheimer says.



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